The present invention relates to non-aqueous concentrates of water soluble polymers to produce polymer-viscosified aqueous solutions to wellbore operations.
Polymer-viscosified aqueous solutions are used for many purposes in the field of drilling, completing and servicing oil and gas wells. Exemplary gravel packing compositions and operations are set forth in the following U.S. Pat. Nos. 5,027,899; 5,058,677; 5,184,679; and 5,251,699. Exemplary acidizing compositions and operations are set forth in the following U.S. Pat. Nos. 3,779,914; 4,487,265; and 5,007,481. Exemplary well drilling and completion fluids are set forth in the following U.S. Pat. Nos. 4,620,596; 4,621,692; and 4,822,500.
Polymer-viscosified fluids require that the water soluble polymers be completely dispersed and hydrated in the aqueous fluids. One method of achieving this is to prepare a concentrate of the water soluble polymer in a liquid which has no appreciable swelling or solvating effect on the polymer. See for example the following U.S. Pat. Nos. 4,312,675; 4,325,861; 4,435,217; 4,726,912; 4,772,646; 5,091,448; 5,278,203; 5,631,313; 5,834,533; and 5,925,182. Concentrates of water soluble polymers in water-in-oil emulsions are disclosed in U.S. Pat. Nos. 4,670,550 and 4,964,999.
We have now developed a water soluble polymer-containing concentrate which has superior stability exhibiting no polymer settling and little to no liquid syneresis on aging at 120xc2x0 F. for 16 hours.
A hydrophilic polymer concentrate composition comprising: a) from about 45% to about 70% of one or more hydrophilic, water soluble polymers; b) from about 0.5% to about 1.5% of an organophilic clay (organoclay) suspension additive; c) from about 0.1% to about 2.5% of a stabilizing agent comprising one or more acids in an amount from about 0.001% to about 1.5%, one or more anionic surfactants in an amount from about 0.001% to about 1.0%, one or more nonionic surfactants in an amount from about 0.001% to about 0.625%, and from about 0% to about 0.75% of one or more water soluble organic liquids; and d) from about 25% to about 55% of a hydrophobic, water insoluble liquid suspension medium.
Unless otherwise indicated herein, the above percentages and percentages indicated hereinafter are weight percentages based on the total concentrate composition weight.
Preferably the stabilizing agent is a microemulsion comprising from about 1% to about 80% water, from about 1% to about 60% of one or more acids, from about 1% to about 40% of one or more anionic surfactants, from about 1% to about 25% of one or more nonionic surfactants, from about 0.5% to about 40% of one or more solvents, and from 0% to about 30% of a water soluble organic liquid, wherein these percentages are weight percent based on the weight of the stabilizing agent and total 100%.
While the invention is susceptible of various modifications and alternative forms, specific embodiments thereof will hereinafter be described in detail and shown by way of example. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but, on the contrary, the invention is to cover all modifications and alternatives falling within the spirit and scope of the invention as expressed in the appended claims.
The compositions can comprise, consist essentially of, or consist of the stated materials. The method can comprise, consist essentially of, or consist of the stated steps with the stated materials.